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There was an ingenious development in submarine construction by the Royal Dutch Navy. The importance of this one unique class of submarines may warrant another look at that, development.

Throughout history there have been numerous interesting designs for submarines; there is no doubt of this. The very first designs were intriguing both in terms of navigation capabilities and weapon platforms. Some designs were a success, and were starting points for new and more innovative designs. Others were not, and sometimes this proved fatal to both crew and craft.

The First World War showed that submarines could, under the right circumstances, be very capable of performing dangerous missions, and be dangerous weapons. Great Britain came close to being totally isolated by the Germans. This served as a lesson to all major seafaring powers, and pressure was put on the various building and design departments in these countries to increase their submarine fleets both in size and capabilities. In the years between the two world wars, a great variety of craft entered service in the various countries. There were submarines with turrets housing “battleship guns.” Some submarines were capable of carrying one or two airplanes in deck hangars or a platoon of marines; others had cargo holds to carry on trade by travelling beneath a force blockading a country’s ports. There were submarines varying in size from one man craft to the very large, long range boats of the United States and Japan.

As the Second World War progressed, the superiority of the German submarine became evident. By the end of the war they had a large number of submarines which ranged from some prewar, small coastal craft, to their most successful TYPE-7 UBoats and newest designs of true submarines of the TYPE-21.

At the end of the Second World War the Netherlands had a submarine fleet comprised of three types of boats. There were the ‘0’ boats built and designed for service in the North Sea and the Atlantic. The ‘K’ boats, larger in size and longer range, were primarily used on the Dutch overseas stations of Indonesia, Suriname and the Netherlands Antilles. Both groups were designed and built by Dutch yards. Finally, to cover war-time losses and keep their forces at a required strength, the Dutch leased a number of surplus British craft.

All the previous developments were the result of only one consideration: staying ahead of what one’s potential opponents are doing. The race for underseas superiority was started by the very first submarine builders, raged during the wars, and continues today with the advent of ultra silent submarines, nuclear power and missiles, closed cycle propulsion systems and state of the art sonar/sensor/detection systems.

During the late ‘forties, however, it was quite clear that the Dutch Navy required replacements for outdated submarines. During the design stages, Mr. M. F. Gunning, a retired Dutch naval designer, came up with a new design that, although not continued in any other class of boats, is interesting to review.

The new design called for an outer hull in the general shape of a triangle, with three individual pressure hulls inside the triangle: the top hull housed the control room, all sensors, weapon systems and crew’s quarters, while the lower two contained the port and starboard engine room, auxiliary engines, motors and generators, as well as battery storage and pumps. These lower pressure hulls were connected to the upper hull in two places only, which also greatly increased the survivability of the submarine as a whole. The design allowed for a fairly large-sized sub to be fitted into a medium-sized hull, therefore not compromising the weapon load she carried, and allowed for an operational diving depth of 1000 feet, which was a remarkable achievement in the late ‘fifties and early ‘sixties.

These boats had a surface displacement of 1494 tons, while submerged they displaced 1826 tons. The maximum speed of the boats in this class was 14 knots surfaced, and up to 17 knots submerged. It is interesting to note, however, that the surface speed was attained by 3100 HP diesels, while contemporary subs like the British PORPOISE class, which were only a few hundred tons larger in size, required 6000 HP Admiralty Standard diesels to achieve the same surface speed. There were a total of eight torpedo tubes: four in the bow and four in the stem of the boal A total of twenty-two reloads were carried on board.

Four boats of this new type were approved by the Dutch government in 1949, and ordered from Dutch shipbuilding companies the following year. As construction started, however, two boats were delayed in order to evaluate the new design and to be able to incorporate changes due to lessons learned from the first two boats. In addition to this, the Dutch were also able to install new technology in the fields of sensors and communications in the last two boats of the class.

Any other boat at that time (and up to the present for that matter) was constructed with a single cylindrical shaped pressure hull. Large boats usually had two decks, but this was achieved simply by inserting a horizontal deck within the one pressure hull. As boats got to be bigger in size, the need arose to use heavier gauge steel for the pressure hull; the only drawback to this principle is that more of the submarine’s weight is used for hull structure and integrity, rather than equipment or machin~ ery. As size increases, weight will increase, which will require more power, which in tum will increase weight … , a vicious cycle.

All four boats in the class (HMNLS DOLFIJN, ZEEHOND, P01VIS and TONUN) were completed between 1961 and 1967, and entered service about a year after completion. The designs were indeed superior at the time, making this class one of the quietest of all; a reputation shared with the British PORPOISFJOBERON boats. These boats fulfilled all requirements placed on their design, and operated for many years without any major problems or incidents. In the late 1970s, they were due for life extension refits, and were all upgraded to the same standards, thereby eliminating any previous differences between the lead boats, and the two followers. As the time came, however, in the seventies, to look for a replacement of some of the older boats still in service, it became increasingly obvious that this design, however successful, was not practical to incorporate in the new class of boats on the drawing board.

During the mid-life refits, the Dutch yard that overhauled the boats found it very difficult to service the diesels. All the engineering spaces were extremely cramped, making normal maintenance a strenuous exercise, and making any speedy overhauls impossible. Added to this, there were some other major concerns and problems that could not be ignored. These had either been overlooked when the DOLFIJN class boats were designed, or simply were not an issue at that time.

One of the main changes to be reckoned with was creature comforts. On the tri-hull boats a hot-bunking system was in place: there were only 50 bunks for 70 crew members. Only two shower stalls were to be found on the whole boat; one in officers country, and one for use by the enlisted men. The one galley that was used for serving the whole crew was only about five square meters in size, while the mess hall could only seat about fifteen to twenty men at a time.

To be incorporated in the next design were larger crew quarters and spaces, better sensors and nuclear propulsion. Although these boats were completed, they were not nuclear powered. All these changes in requirements, habitability, range and load, meant that the triple hull design was a one time only trial. While a successful design, it was not to be continued in further Dutch classes for the reasons stated.

When I had the opportunity to go on a tour of HMNLS DOLFUN in the early 1980s, it became evident to me how cramped indeed these subs were. A visit to a USS BARBEL class sub in 1986 showed that, even though this was an old and cramped sub by the standard of nuclear submarines, it was spacious when compared to the Dutch tri-hull design. This could well be the end of the story, for the Dutch never did pursue the ideas, principles and lessons learned from this type ofboal.

There is, however, a different ending here. Several sources, including the book Combat Arms/Modem Submarines by David Miller, report that the Soviet TYPHOON class ballistic missile submarines also are designed using multiple hulls. It is assumed that there are two hulls, side by side, on the bottom. Each of those cylinders would contain one row of missiles, forward torpedo tubes, one reactor, and engineering compartment containing the propulsion to the propeller. A third pressure hull is located on top of the other two, but it extends only over part of the length of the sub: it is situated under the sail, and contains crew quarters, all weapons and sensor controls. This is similar to the Dutch design, although these subs must certainly be roomier than the original Dutch version. As the total displacement is around 25,000 tons, this means that each hull would be quite sizable by itself, and it would be impractical to construct this behemoth using one gigantic pressure hull. Again, here the design surely has survivability, habitability, and time to be spent on station as the grounds for the design and layout of this class of submarines.

So it appears that the triple, or multiple, pressure hull designs in submarines are again in the news. What further developments are in progress, or being studied at this time, is not known. Whether the Soviets will pursue this design into the next generation of submarines will depend on how effective the design is, (as far as serviceability and routine maintenance is concerned) and what economic, political and strategic constraints are encountered in this decade.

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